This invention relates to a conveyor, and in particular to a shingle bundle palletizer with an improved metering conveyor, pattern conveyor, and shuttle conveyor and a method of using the same.
Typically, asphalt shingles are packaged into a bundle containing numerous shingles. For example, about twenty-seven asphalt shingles may be packaged into a bundle weighing about fifty pounds. After the shingles are packaged into bundles, the completed bundles enter a palletizer where the bundles are stacked onto pallets. The bundles enter the palletizer by travelling along a bundle metering conveyor, which assures that the bundles enter the palletizer at a fixed rate, such as, for example, about thirty-five bundles per minute.
There are well-known devices for metering articles on a conveyor system. For example, U.S. Pat. No. 4,443,995 to Myers et al. appears to disclose a metering device including a lower conveyor and an upper conveyor. The conveyors include a pair of transversely spaced chains. The conveyor and the conveyor belts have the same rate of forward movement. The articles that are supported by the sets of support bars will be maintained in position by the cooperating sets of carrier bars, respectively. A ramp may be used to elevate the articles supported by the bars onto a conveyor. The articles pass from the metering device to a packaging unit. The packaging unit includes a speed-up conveyor which has a linear speed greater than that of the conveyor and the conveyor chains. In another example, U.S. Pat. No. 4,682,684 to Lothman appears to disclose a pair of conveyors with conveyor belts. One conveyor belt rotates at twice the linear speed of the other conveyor belt such that an object is propelled along the first conveyor belt at twice the speed of the second conveyor belt.
After the bundles enter the palletizer at a fixed rate from the metering conveyer, a pattern conveyor then arranges the shingles by turning some of the bundles 90 degrees so that they will be in the appropriate pattern to be stacked onto the pallet. Typically, each layer of bundles on the pallet has the lengthwise direction of the bundles at a 90 degree angle to the bundles in the adjacent upper and lower layer.
Many conventional devices for arranging articles in a desired orientation on a conveyor system are known in the art. For example, U.S. Pat. No. 5,316,123 to Achelpohl appears to disclose an apparatus for arranging pieces in a flat position. The apparatus includes an upper conveyor belt that runs above a table, and a lower conveyor belt that runs below the table. The conveyor belts run at the same circumferential speed. A third, relatively short conveyor belt runs parallel to and at the same circumferential speed as the conveyor belts. As the workpiece moves along the conveyor belts, a clamping pin engages the workpiece to rotate the workpiece 90 degrees. Two stops on a pair of transfer belts running at the same circulating speed as the conveyor belts prevent any further rotation of the workpiece.
In another example, U.S. Pat. No. 5,660,262 to Landrum et al. appears to disclose an apparatus including variable speed motors for driving a chain, a drive element, and an infeed conveyor, respectively. The drive element is preferably a plurality of elastomeric O-ring belts which provide the composite feeding/turning action to successive cartons as they travel from the infeed conveyor to a take away conveyor. A microprocessor is used to control the stepper motors in order to maintain the desired position of the successive cartons.
After the bundles are arranged in the proper orientation on the conveyor system, a shuttle conveyor then receives a layer of bundles of shingles and, at the appropriate time, propels them onto the top of the stack of bundles on the pallet.
There exist some conventional devices for loading items from a shuttle mechanism onto a loading device. For example, U.S. Pat. Nos. 3,499,551, 3,507,411 and 3,625,376 to McWilliams appear to disclose an apparatus for loading mail bags from a loading dock into a loading vehicle. The apparatus includes an elevating mechanism and conveyor. The elevating mechanism comprises a pair of cross levers that are pivotally mounted to a platform and a wheeled frame. One of the levers can be drawn forward of the wheeled frame by a screw and nut device to raise the platform from a lowered position to an upper position.
In conventional devices, the shuttle is driven forward and rearward by a main air cylinder. Two cushioning air cylinders cushion the end of travel of the shuttle in the forward and rearward directions. The movement of the shuttle in the prior art shuttle conveyor design is somewhat imprecise because of the variability introduced by the air cylinders which operate differently under different temperature and humidity conditions. Also, lubrication variations in the moving parts can affect the preciseness of the motion.
There is a need to provide a improved bundle metering conveyor that includes an upstream belt mechanism which can supply the bundles at a first feed rate, and a downstream belt mechanism to take away the bundles at a second, faster bundle takeaway rate. In addition, there is a need to provide an improved pattern conveyor in which the speed of the belt rotation can be selected by use of a variable speed motor for driving one or more belts that can be decoupled from one another. Further, there exists a need for an improved shuttle conveyor with a drive mechanism which can precisely reciprocate the shuttle conveyor and control the exact location of shuttle conveyor.
The above objects as well as other objects not specifically enumerated are achieved by a bundle palletizer comprising a bundle metering conveyor for providing bundles at a desired rate, a pattern conveyor downstream of the bundle metering conveyor for orienting the bundles provided by the bundle metering conveyor in a desired orientation, and a shuttle conveyor downstream of the pattern conveyor for stacking the bundles from the pattern conveyor.
According to this invention, there is also provided a bundle metering conveyor comprising one or more upstream belts, a first motor for driving the one or more upstream belts, one or more downstream belts, and a second motor for driving the one or more downstream belts.
According to this invention, there is also provided a pattern conveyor comprising a pair of outer pattern belts rotatably mounted on a pair of outer pulleys, and a center pattern belt rotatably mounted on a center pulley. The outer pulleys are keyed to a pulley shaft, and the center pulley is free-rotating about the pulley shaft, thereby decoupling the center pattern belt from the pair of outer belts.
According to this invention, there is also provided a shuttle conveyor comprising a belt made of elastomeric material, a variable-speed servo motor connected to a drive shaft for driving the belt, and an encoder for reading indicia on the drive shaft, thereby enabling a determination of a rotational speed of the drive shaft and a position of the shuttle conveyor.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.